The invention relates to a tank ventilation device for a motor vehicle in which a tank can be filled with fuel via a filling tube. One side of a ventilation device is connected to the filling tube and the other side to an accumulator for gaseous hydrocarbons.
DE 10 2008 061 A1 relates to a fuel container which can be filled via a filling tube. A ventilation device is connected to the filling tube close to a mouth of the filling tube. Via this ventilation device gaseous hydrocarbons which where displaced during the refueling out of the fuel container can be conducted to an activated carbon filter in which the gaseous hydrocarbons are accumulated. Inserting a nozzle into the mouth of the filling tube causes a pivoting of a flap which carries a cup-shaped closing body. The closing body then closes the inlet into the ventilation device so that no liquid fuel can enter from the filling tube into the ventilation device. However, fuel can still be conducted to the activated carbon filter via the ventilation device.
In a tank ventilation device disclosed in U.S. Pat. No. 5,103,877 A, a very complex valve is provided at a connector of the filling tube which leads to the activated carbon filter of the ventilation device. The valve is opened by inserting the nozzle into the mouth of the filling tube. It then allows gaseous hydrocarbons to pass, however, it prevents liquid fuel from entering the ventilation line.
In the embodiment according to U.S. Pat. No. 4,932,444 A and in the embodiment according to U.S. Pat. No. 4,747,508 A, a float ball prevents fuel from reaching the activated carbon filter from the filing tube via the ventilation line. According to U.S. Pat. No. 4,932,444 A an access on the side of the filling tube to the ventilation line is closed by means of a valve disc which is lifted as a result of removing a tank lid from the filling tube. Therefore, when the tank lid is closed, the ventilation line to the filling tube is blocked. When the tank lid is open and the filling level of the tank is high in the filling tube, the float ball closes the access to the ventilation line. According to U.S. Pat. No. 4,7474,508 A, the float ball is also pushed into a valve seat by means of a lever when the tank lid is closed, so that an access on the side of the filling tube to the ventilation line is closed.
Object of the present invention is to provide a tank ventilation device of the above-mentioned type in which the ventilation line has a further function, wherein liquid fuel is prevented from entering the ventilation line with simple measures.